Some will tell you otherwise, but my honest opinion, considering the eggs haven't dimpled is to leave them be for a few more days. Many people cut the eggs even when there isn't dimpling going on and I have done so as well but I have had a few things happen that I wasn't too fond of. If you cut too early, you're allowing the fluid in the egg get moldy (this happens as soon as air hits it). Depending on where the incubator is and the environment around it, you're increasing the chance of a fly laying eggs that will hatch in to maggots. THIS HAS HAPPENED TO ME! Snake turned out fine, but I did not like the snake sitting in rotting fluid full of maggots. I care too much for my snakes to let that happen again just to see what I've got a few days early.
Now if the eggs are completely dimpled and almost like dried out, I might cut. The dimpling means the fluids have been absorbed and you're chances of what I mentioned above is far less likely to occur. When they're that dimpled, they are pretty much ready to come out.